Treatment of hydrocarbon oils



Oct. s, 193.5.

L. c. HUFF l TREATMENT OF HYDROCARBON OILS Filed March 30, 1951 fic?? 252 zw: Een 6 Huff RNNNUQAWI MBQQ uvas? www A BSN Patented Oct. 8, 1935 UNITED STATES PATENT OFFICE TREATMENT OF HYDROCARBON OILS Application March 30, 1931, Serial No. 526,239

2 Claims.

Ihis invention relates to the treatment of hydrocarbon oils, and particularly refersy to an improved process and apparatus for the conversion of hydrocarbon oils in combination with which is operated a process for separating relatively light components from crude oil. I

The primary concepts of the invention provide an improved process for the conversion of relatively heavy oils into more desirable lower boiling products, heat recovered from the gaseous and liquid products of the conversion being utilized in the distillation of crude oil for the purpose of removing the naturally-contained relatively light fractions thereof;

A more specific embodiment of the invention may comprise supplying raw oil charging stock to one or a plurality of heating elements, introducing the heated oil into an enlarged reaction zone, withdrawing liquid and vaporous products from said reaction zone to a vaporizing zone preferably lmaintained under reduced pressure; withdrawing residual liquid from said vaporizing zone, subjecting vapors from said vaporizing zone to fractionation, returning refiux condensate from the fractionator to the aforementioned heating zone or zones for further conversion; subjecting the desirable light components of the fractionated vapors to condensation and cooling and collecting resulting products, passing a crude oil in indirect heat exchange relation with the relatively hot cracked vapors and in indirect heat exchange relation with the relatively hot residual oil from the cracking system and thence supplying the heated crude to a topping system wherein the relatively light components thereof may be vaporized, the vapors subjected to fractionation and their desirable light components condensed and collected.

As a special feature of the present invention the heating Zone of the cracking system may comprise a plurality of separate furnaces and heating elements of any desired form, the oil to be treated preferably being supplied in part to each of the heating elements simultaneously and the streams of heated oil commingling and passing into the reaction chamber. Substantially the same conversion conditions are preferably maintained in each heating element.

The attached diagrammatic drawing will serve to more clearly illustrate the principles and features of the invention.

The raw oil charging stock to be cracked may be supplied through line I and valve 2 to pump 3 from which it may be supplied through line 4, line 5 and valve 6 to fractionator 1, wherein it may be preheated by Contact with the relatively hot vapors in this zone and may pass together with the insuciently converted components of the vapors which may be condensed in the Zone through line 8 and valve 9 to pump I0. Pump I 0 may supply the reflux 5 condensate from fractionator 1, alone or together with preheated raw oil as the case may be, through line II and valves I2 and I3 to the heating zone of the system. A portion or all of the raw oil may, instead of passing overhead to fractionator 1, 10 pass directly through valve I4 in line 4 into line I I and thence through valve I3 to the heating zone together with the oil supplied from pump I0 as already described.

The heating zone which is here illustrated coml5 prises two separate .heating elements I5 and I 6 located respectively in suitable furnaces I 1 and I8. Substantial equal amounts of oil are preferably supplied simultaneously to each of the heating elements from line II through lines I9 and 20 con- 20 trolled respectively by Valves 2I and 22. The divided streams of oil are preferably subjected to substantially the same conversion conditions in each heating element and may be discharged through lines 23 and 24 controlled respectively by 25 valves 25 and 26 into line 21, wherein the two streams may be commingled and may pass to reaction chamber 28. Preferably a substantially superatmospheric pressure is employed in the heating zone and in the reaction chamber. The 30 pressure employed in the reaction chamber may, if desired, be lower than that employed in the heating zone. Preferably the pressures employed in the two heating elements are substantially the same. 35 Preferably both vaporous and liquid products are withdrawn from chamber 28 through line 29 and valve 3!) to vaporizing chamber 3I, wherein the vapors and residual oil may be separated. The residual liquid may be withdrawn from the 40 system to cooling, and storage or any desired further treatment through line 32 and valve 33, heat exchanger 34 and line 35. Vapors may pass from chamber 3| through line 36, valve 31, heat eX- changers 38 and 39 and line 40 to fractionator 1, 45 from which reflux condensate may be returned, as already described, for reconversion. A portion of the vapors and gases from chamber 28 may, if desired, be withdrawn through line 51 and valve 58 and may be introduced into the lower 50 portion of fractionator 1 in direct contact with the reflux condensate accumulated therein to reboil this product and substantially free it of entrained desirable light materials. The relatively light desirable components of the vapors 55 subjected to fractionation may be Withdrawn from the fractionator through line 4l and valve 42,-may be passed through heat exchanger 43 to be subjected to condensation and cooling in condenser 44, products from which may pass through line 45 and valve 46 to be collected in receiver 41. Uncondensable gas may be released from the receiver through line 48 and valve 49. Distillatermay be withdrawn through line 50 and valve 5l. A portion of the distillate may, if desired, be withdrawn from receiver 41 through line 52 and valve 53 and may be recirculated by means of pump 54 through line 55rand-valve A56 5to Tthe upper portion of fractionator 1 to assist fractionation of the vapors in this zone. y

A crude oil containing a substantial proportion of light components such as gasoline may be'supplied through line Eiland valve 6| 'to-pump 62, from which i-t may be fed through line 63Y and valve 64 to heat exchanger 43 where it may be preheated by indirect contact `with vapors from fractionator` 1. The crude oil may thence pass through line 65 to heat exchanger 34 rwhere it may be further preheated by indirect vheat Aexchange relation with residual oil withdrawn from chamber 3| and from which it1may pass through line 65 to heat exchanger 39. Heat exchanger 39 may be located in the path ofvapors passing from chamber 3| to fractionator 1 and the crude oil supplied therethrough may receive additional heat by indirect kcontact with these vapors passing therefrom through line 61 and valve-.68 into the. topping zone or -fractionator 69.

It will be understood tha-t any or all the heat exchangers mentioned may be utilized Vfor the purpose `of preheating the crude oil and if desired additional heat maybe supplied to the crudefrom the cracking system orV from any external source not illustrated in the drawing. The crude oil is preferably heated suiciently to eiect vaporization of a substantial portion of the oil including the llight componentsV which are to be separated. The vapors Amay-be subjected to :fractionation in column 69 to effect nal separation of the desirable Vlight components of tne crude whichv may pass through line 10 and valve 1I, may be subjected to condensation and `cooling in condenserr12, products from which may pass through line 13 and valve 14 to -be collected-in receiver 15. -If desired, side s-treamsof somewhat higher boiling products maybe `withdrawn from the fractionator, for example, vthrough line81 and valve 88, to be separately cooled and collected. Uncondensable gas Ymay be released from the receiver 15 through line 16 and valve 11. The 4distillate may be withdrawn `through line 1B and valve 19. A portion of the distillate may be, if desired, withdrawn from receiver 15 through line and valve 8| and may be recirculated by means of pump 82 through line 83 and valve'84 to the upper portion of f-ractionator69 to assist in maintaining the desired outlet temperature and to assist inmaintaining the desired degree of fractionation in this zone. The topped crude oil, that is, that portion ofthe crude remaining unvaporized or condensed in fractionator 69, may

be withdrawn from the fractionator through line 85 and valve 86 to cooling and storage or to any desired further treatment. If desired, a portion or all of this oil may comprise a portion or all ofthe charging stock supplied to the cracking process and may be introduced into line I through line 89 and valve 99, passing thence to pump 3 to be supplied therefrom to the cracking system as already described.

Pressures employed in the cracking system may range from atmospheric to superatmospheric pressures as high as 2000 pounds per square inch or more, the preferred range being between and 1000 pounds per square inch. Substantially equalized pressures may be em'- ployed throughout the cracking system or differential pressures may be utilized between any of the various elements. Preferably a substantial reduced pressure is employed in the vaporizing chamber and in succeeding fractionating,

condensing and collecting equipment of the cracking system relative to that employed in the conversion Zone. Conversion temperatures employed may range from 800 to l200 F. more or less. The preferred temperatures range between 850 to 900 F. The specific conditions chosen depend on the charging stocks and the results desired. The topping system may be operated under substantial atmospheric, subatmospheric or superatmospheric pressures.

As a specific exampleof operating conditions which may be employed'in the practice of the present invention and results which may be obtained therefrom, a crude oil containing ap- 25 proximately 30% of material coming within the boiling range of motor fuel is heated to a temperature of approximately 550 F. by heat recovered from the cracking system and the evolved vapors are subjected to fractionation under substantially atmospheric pressure. A temperature of about 425 F. is maintained at the top of this fractionating zone and the straight run gasoline is condensed and collected. Topped crude meeting market specications for bunker A fuel oil is withdrawn from the fractionator or topping zone. The charging stock supplied to the cracking system consists of a blend of approximately 15% topped crude from the topping operation previously described, about 15% of a relatively low grade crude oil containing substantially no motor fuel and about 10% of pressure distillate bottoms from another cracking operation. This oil is subjected in the two heating elements to a temperature of about 930 F. under a superatmospheric pressure of about 300 pounds per square inch. Substantially the same pressure is utilized in the reaction chamber but is reduced in the vaporizing chamber and succeeding portions of the cracking system to approximately 35 pounds per square inch. This operation may yield approximately 60% of gasoline based upon the topped crude oil having an anti-knock value approximately equivalent to a blend of 60% benzol and 40% straight run Pennsylvania gasoline. In addition, about 30% of good quality fuel oil is produced by the cracking operation, the remaining products being uncondensable gas and a relatively small percentage of coke or carbonaceous material.

I claim as my invention:

1. A hydrocarbon oil conversion process which comprises subjecting the oil to cracking conditions of temperature and pressure in a cracking zone and separating the same into vapors and unvaporized oil, passing crude oil in indirect heat exchange relation with vapors from the separating step and heating the crude to the Vaporizing temperature of lighter fractions thereof, releasing such lighter fractions from the crude in a vaporizing Zone and condensing and collecting the same, flash distilling the unvaporized oil by pressure reduction and combining resultant flashed vapors with the first-mentioned vapors, dephlegmating the commingled vapors in direct contact with unvaporized portions of the crude in a fractionating zone independent of said vaporizing zone, supplying the resultant mixture of reux condensate and unvaporized crude oil to the cracking zone, and finally condensing the dephlegmated vapors independently of the vapors of said lighter fractions of the crude.

2. A conversion process which comprises subjecting hydrocarbon oil to cracking conditions of temperature and pressure in a cracking zone and separating the same into vapors and residue in a separating zone maintained under lower pressure than the cracking zone, passing crude oil in indirect heat exchange relation with heated products from the separating zone and heating the crude to the vaporizing temperature of lighter fractions thereof, discharging the heated crude into a vaporizing zone apart from the separating zone and releasing the lighter fractions thereof as vapor in this zone, removing such separated crude oil vapors from the vaporizing zone and condensing and collecting the same, passing vapors from the separating zone into a fractionating zone independent of said vaporizing zone, removing unvaporized portions of the crude from the vaporizing zone and introducing the same into said fractionating zone, dephlegmating the vapors in the fractionating zone in contact With said unvaporized portions of the crude and supindependently of said separated crude oil va- 15 pors removed from said vaporizing zone.

LYMAN C. HUFF, 

